DESCRIPTION (Applicant's Abstract): In their first several years of language learning, children acquire roughly 15,000 words. Understanding how they learn so many words so quickly is fundamental to understanding a critical aspect of human cognition: How natural predispositions interact with learning to carve the world into the categories encoded by language. Answering this question is, in turn, a prerequisite for understanding disorders in language learning and the often observed links between language disorders and other learning disabilities. In this research, the investigators will examine a "shape bias" in young children's and adults' word learning. As first reported by Landau, Smith, & Jones (1988), 2- and 3-year-olds and adults who are shown a novel object and hear it named later extend the name to other objects that are the same shape as the exemplar, regardless of variations in texture or size. The purpose of the proposed research is to move the study of naming and its special relation to shape in a new direction. Current research in adults' perception of shape suggests that static properties of shape may interact with substance and motion to inform observers about rigidity, which then may guide attention towards or away from shape. Furthermore, natural versus man-made textures may inform observers about an object's category, and hence which kinds of properties may be most important for membership. The investigators ask how specific aspects of shape and their interaction with material and texture influence categorization and naming by children and adults. The present research consists of ten experiments designed to examine three issues: 1) How different properties of static shape and their interactions with material guide children's and adults' generalization of a new word to new exemplars. 2) How differences between natural and man-made textures might affect naming and categorization, specifically whether objects with these different texture types invite subjects to generalize to different types of objects. 3) How higher-level conceptual knowledge affects subjects' inferences about the range of possible shapes included in a named category. In each experiment, subjects are 2-, 3-, and 5-year-olds and adults. In the basic method, subjects are presented with novel 2- or 3-dimensional objects or materials. In the Word condition, the stimulus is named; in the Similarity condition, it is not named. Then subjects decide whether other objects can be called by the same name, or they decide whether the other objects are "like" the exemplar. These methods duplicate events that naturally occur during language learning.